Various means have been used in the prior art to design warheads with a "follow-through" capability for effectively attacking a target behind protective armor. These prior art means have included warheads having a shaped-charge which attempted to first punch a hole through the armor and then follow-up by either starting fires or injecting lethal fluid chemicals. Some of these prior art shaped-charge devices attempted to solve this problem by using bimetallic liners using naturally pyroforic materials, such as zirconium. These shaped-charge warheads comprised the usual combination of a hollow explosive lined with a metal. The metal liner was composed of an inner metal material, such as copper or aluminum, and an outer liner metal made of pyroforic metal. The inner liner material formed the stretching jet, whereas most of the outside liner material went into a slow-moving rearward slug. The stretching jet was designed to form a hole through the outside armor of a vehicle through which the pyroforic slug could then enter to defeat the target. The problem with this type of shaped-charge warhead was that the slug was frequently too large to pass through the hole in the outside armor. Other prior-art devices attempted to solve this problem by using a bimetallic liner wherein the naturally pyroforic material was used on the inside of the liner. However, the problem with these devices was that the naturally pyroforic material does not form good stretching jets and, thus, their ability to make a hole through outside armor is quite low.
Other prior-art shaped-charge warhead projectiles attempted to produce an effective follow-through capability by using a follow-through projectile that was supposed to enter the armored vehicle through the hole produced by the stretching jet. The follow-through projectile was found to work only if the follow-through projectile impacted the target without pitch or yaw, the vehicle armor was relatively thin, the follow-through projectile did not get stuck in the armor, and guides were used for the follow-through projectile. The problem with these shaped-charge follow-through projectile munitions was that the guides added considerable weight to the projectile. Prior-art shaped-charge munitions using fluid flow-through means were also not successful because almost all of the fluid was dispersed on the outside surface of the vehicle armor even when the armor was relatively thin.
Another problem with prior-art shaped-charge devices has been that, because of the small diameter of the shaped-charge jet, there was a corresponding small probability of hitting crew members in an armored vehicle. The probability of catastrophic defeat of an armored vehicle depends critically upon the impacting munition ability to cause ammunition within the vehicle to explode or burn, igniting the vehicle's fuel, or generating steel debris, called spall, off the exit side of the perforated armor. The steel debris moves in a divergent fashion from the shot-line and, hence, can lethally encompass a large percentage of the crew compartment.